Fig. 1From: Estimation of the proper gap ratio using preoperative radiography for posterior tibial slope maintenance in biplanar open wedge high tibial osteotomyReason for the difference between anterior gap and posterior gap. a Horizontal striped arrow: desired osteotomy direction, vertical striped arrow: real osteotomy direction, b The anterior gap (AG) and posterior gap (PG) are not measured in one plane, c AG should be smaller than PG, geometricallyBack to article page